Such systems for loading sheet materials on a rotary drum are disclosed by Japanese Patent Publication No. 56-24270, or Japanese Open Patent Publication No. 59-171676, for example.
In the former publication, the system involves a suction opening which suckes back surface of the sheet materials at the leading end. And in the latter publication, the system involves a clamp mechanism (gripper) for clamping the leading end of the sheet materials.
In such system, it is desirable that the sheet materials perfectly contact with the peripheral surface of the drum. But, according to these prior arts, it is found that there are partial spaces between the sheet materials and the peripheral surface of the drum sometimes.
Therefore, in case that these prior arts are applied to an electrophotocopying machine of CPC type, the image is out of focus at the risen part from the drum surface, making the sharpness lower, and liquid developer invades into the partial spaces between the sheet materials and the peripheral surface of the drum, blotting the back of the sheet materials.
And in case that these prior arts are applied to a rotary press for light printings, which uses a master paper as sheet forms, inks enter into the spaces between the master paper and the drum and decreases the value of goods when they are adhered to the margine part of the paper. Moreover, the master paper is partially spaced from the drum by the centrifugal force during high speed printing.
The suction opening is desirable for making no turning-in at the leading end of the sheet materials. But, it may allow of the slip or creases of sheet materials, which may be fatal defects for color copying obtained through several different color developments on one developing paper by a color electrophotocopying machine or the like, especially, when the spaces mentioned above is broken out.
When hard or thick sheet materials are used, the sheet materials is tending to rise from the drum surface by the reaction of cylindrical bending along the drum, in comparison with the different case in which the sheet materials are laid on a flat form. Therefore, there is limitation of the sheet materials in thickness or hardness thereof.
Therefore, the object of the present invention is to propose a system for loading sheet materials on a drum, which disadvantages abovementioned are resolved.